On the breezy island of Sm\u00f8la, located off the central coast of Norway, a modest experiment involving a can of black paint has emerged as one of the most frequently referenced pieces of proof that wind turbines and birds of prey can coexist without conflict. Researchers associated with the Norwegian Institute for Nature Research (NINA) coated one blade black on four turbines at the Statkraft-managed Sm\u00f8la wind farm in August 2013, subsequently dedicating the next three and a half years to counting carcasses found beneath them. The findings, released in 2020 in the journal Ecology and Evolution, are significant enough that they continue to be referenced by wind industry developers and conservation organizations six years later. Additionally, the authors themselves acknowledge that the sample size is small enough that these results should be viewed as an encouraging possibility rather than a definitive solution.<\/p>\n
The reason Sm\u00f8la became a testing ground<\/p>\n
Sm\u00f8la\u2019s wind farm, which achieved its complete set of 68 turbines in 2005 after starting with 20 in 2002, is located on an island that also supports one of Norway\u2019s most densely populated breeding groups of the white-tailed eagle, Haliaeetus albicilla. Long before the paint study was conducted, the area had already been established as a well-documented example of raptor collision risks: NINA researchers had spent years monitoring eagle fatalities using satellite telemetry and systematic carcass recovery, making Sm\u00f8la one of the best-observed wind farms regarding avian mortality worldwide.<\/p>\n
This historical monitoring laid the groundwork for the painted-blade study. Since NINA had already amassed years of baseline carcass data for specific turbines, the team was able to analyze fatality trends before and after modifications to the turbines, rather than depending on a singular before-and-after comparison at an unfamiliar location.<\/p>\n
The method of the experiment<\/p>\n
In the first week of August 2013, technicians painted one of the rotor blades black on four turbines at Sm\u00f8la. Four nearby, unmodified turbines functioned as controls. A team led by Roel May then compared carcass counts at the eight turbines over two periods: 7.5 years of monitoring prior to the paint application (2006 through July 2013) and 3.5 years post-application (August 2013 through the end of 2016), using standardized searches paired with trained detection dogs conducted throughout both phases.<\/p>\n
The primary figures, excluding willow ptarmigan (a ground-dwelling grouse tracked separately in a related study), were as follows: at the four painted turbines, researchers recorded 11 bird carcasses in the pre-treatment phase and 6 afterward. At the four unaltered control turbines, the carcasses increased from 7 beforehand to 18 after. This difference \u2014 fatalities decreasing at the painted turbines while more than doubling at their unpainted counterparts \u2014 forms the crux of the study\u2019s conclusions, allowing the authors to estimate a 71.9% reduction in the annual fatality rate at the painted turbines compared to the controls, with a 95% confidence interval approximately between 62% to 79%.<\/p>\n
Specifically for white-tailed eagles, the trend was even more pronounced. Prior to painting, six eagle carcasses were recovered at the four turbines that were subsequently painted, and none at the four control turbines. Following the painting, no eagle carcasses were discovered at either the painted or the control turbines until the study concluded. This eagle-specific statistic \u2014 six fatalities reduced to none \u2014 has been widely circulated in media reports about the study, sometimes without emphasizing that the corresponding rise in fatalities at the control turbines (from 7 to 18) encompasses all bird species documented, not solely eagles; no white-tailed eagle carcasses were recorded at the control turbines in either timeframe.<\/p>\n
The significance of a black blade<\/p>\n
The researchers suggest a straightforward mechanism: motion smear. A rotating rotor blade, particularly one with a uniform light color against a bright sky, can become challenging for a bird’s vision to identify as a solid, moving entity \u2014 a phenomenon occasionally compared to how a fan blade appears to vanish when in motion. By painting one of the three blades black, the uniform rotor disc is disrupted, creating a visual contrast that the researchers theorized would make eagles and other birds more likely to perceive and steer clear of the turbine while flying toward it. This concept builds upon decades of research on \u201cmotion smear\u201d and visibility of objects in avian flight behavior, although the Sm\u00f8la study did not directly examine eagle flight patterns or avoidance actions \u2014 it focused on measuring fatalities instead.<\/p>\n
The authors’ own cautions<\/p>\n
The paper is notably transparent about its limitations, and that prudence should be considered in any discussions about the findings. The study investigated four treated turbines compared with four control turbines at a single wind farm \u2014 a limited sample that the authors advise necessitates careful interpretation. They state explicitly that they \u201cmust therefore be careful what we deduce from the experiment given the<\/p>\n","protected":false},"excerpt":{"rendered":"
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